Lixiang Wei, T. A. Lipo, Ho Chan, “Matrix Converter Topologies with Reduced Number of Switches”, Proc. of PESC 2002, vol. 1, pp. 57-63 (2002) describes a direct power converter with a DC link. In the direct power converter, a converter and an inverter are connected through the DC link to each other.
The converter converts an AC current on an input side to a DC current and outputs it to the DC link. The converter main circuit described therein is incapable of performing conversion opposite thereto, that is, converting the DC current of the DC link to the AC current and outputting it to the input side. Therefore, the converter cannot regenerate the induced current of an inductive load that is generated when the inverter is interrupted to the power supply side.
Accordingly, in Lixiang Wei, T. A. Lipo, Ho Chan, “Matrix Converter Topologies with Reduced Number of Switches”, Proc. of PESC 2002, vol. 1, pp. 57-63 (2002), the clamp capacitor is provided in the DC link and the above-mentioned induced current is absorbed by the clamp capacitor.
Further, a filter composed of a reactor and an input capacitor is provided on the input side of the converter. Therefore, if the converter is brought into conduction when the clamp capacitor is discharged, the input capacitor and the clamp capacitor are short-circuited to each other, leading to a possibility that an inrush current may flow from the input capacitor to the clamp capacitor.
The technology capable of solving the above-mentioned problem is described in, for example, J. Schonberger, T. Friedli, S. D. Round and J. W. Kolar, “An Ultra Sparse Matrix Converter with a Novel Active Clamp Circuit”, Proc. of PCC-Nagoya 2007 (2007). J. Schonberger, T. Friedli, S. D. Round and J. W. Kolar, “An Ultra Sparse Matrix Converter with a Novel Active Clamp Circuit”, Proc. of PCC-Nagoya 2007 (2007) describes that, in the direct power conversion circuit with a DC link that includes a clamp circuit, the diode rectifier circuit for charging the clamp capacitor is separately provided.
K. Mino, S. Herold and J. W. Kolar, “A Gate Drive Circuit for Silicon Carbide JFET”, Proc. of IECON '03, pp. 1162-1166 (2003) and F. Schafmeister, S. Herold and J. W. Kolar, “Evaluation of 1200V-Si-IGBTs and 1300V-SiC-JFETs for Application in Three-Phase Very Sparse Matrix AC-AC Converter Systems”, APEC '03 (2003) disclose the technologies related to the present invention.